On Friday, Pamella DeVos staged her New York Fashion Week runway show for the Fall-Winter 2017 collection of her evening-wear line, Pamella Roland. Pamella and Betsy are married to brothers, Dan DeVos and Dick DeVos, who are sons of Richard DeVos, a billionaire founder of Amway.

More than 300 people attended the fashion show, where they ogled aubergine crepe gowns, cashmere coats with fox fur cuffs and numerous sequined numbers, as models strode down the runway to tunes such as Michelle Gurevich’s “Russian Romance.” The education secretary, however, was not among them. Hours earlier, she was booed and harangued by protesters outside of a school in Washington that she had come to visit.

Despite her sister-in-law’s absence, in an interview backstage, Pamella said Betsy had been an ardent supporter of the fashion line since it was introduced in 2002. “She wears it beautifully; she’s tall and thin and has been one of my best customers,” the designer said.

Of the hoopla surrounding her sister-in-law’s nomination and confirmation, Ms. DeVos said, “It’s crazy because, I’m telling you, she’s very smart and she knows what she was walking into. She can handle it. But no one would do this if she didn’t have a love of education of the children.”

Ms. DeVos has tried to keep her public and fashion personae apolitical. Though some captions in her Instagram feed link to one of her daughter’s accounts where the DeVos family’s enjoyment of President Trump’s inaugural festivities are on full display, Ms. DeVos avoids connecting her brand to her family, which gave financial support to Mr. Trump’s presidential campaign.

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A look from the Pamella Roland fashion collection designed by Pamella DeVos.CreditSlaven Vlasic/Getty Images

As to why, consider the response of some in attendance when they learned of her family connection.

Just before the lights went down, Sarah Gerrish, the fashion market director at Redbook settled in at her assigned seat next to Aja Mangum, a freelancer editor covering the show for Modern Luxury publications. Both said they had second thoughts about being at the show when they learned of Pamella Roland’s ties to Mr. Trump.

“I questioned my attendance,” Ms. Gerrish said, noting that she was speaking of her personal convictions, not for her employer.

“It gave me pause,” Ms. Mangum said, adding, “But we really don’t know what Pamella’s politics are, just because of the family she’s from.”

For Ms. DeVos, it is not just her customers response she is worrying about. “You have to think about the people who work for you, too,” Ms. DeVos said. “We don’t want to bring that kind of craziness in.”

Nevertheless, Ms. DeVos will continue to dress her sister-in-law, the education secretary, as well as other visible women in the nation’s capital. This is nothing new. “We’ve always had a presence in Washington,” she said.

While models were primping and Ms. DeVos was giving interviews, the designer’s husband glad-handed in the front of the house, greeting family friends as they joined fashion buyers and editors in the large space, darkened by the drawn floor-to-ceiling shades.

A small hubbub surrounded the actress Vanessa Williams, dressed in a white Pamella Roland strapless jumpsuit. Ms. Williams likes Ms. DeVos’s designs (she wore one to her May 2016 wedding) because Ms. DeVos is “a woman of a certain age and her pieces are mature without being old-ladyish,” she said, looking not the slightest bit old-ladyish.

She is not Ms. DeVos’s only celebrity fan. Just a few days earlier, the singer and songwriter Rachel Platten appeared at the Red Dress Collection event, held in honor of the American Heart Association, wearing a red Pamella Roland gown. She also wore a Pamella Roland gown to the American Music Awards last November. Ms. Platten is best known being a writer of “Fight Song,” the unofficial anthem for the Hillary Clinton presidential campaign. On Nov. 8, Ms. Platten posted on Instagram a photograph of a campaign button that says, “A Woman’s Place is in the White House.” She captioned it “#ImWithHer,” likely referring to Mrs. Clinton, not either of the Ms. DeVoses.